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The concept of the 'BRCAness' phenotype implies the properties that some sporadic breast cancers (BC) share with BRCA1/2-mutation carriers with hereditary BC. Breast tumors with BRCAness have deficiencies in homologous recombination repair (HRR), like BRCA1/2-mutation carriers, and consequently could benefit from poly-(ADP)-ribose polymerase (PARP) inhibitors and DNA-damaging chemotherapy. Triple-negative breast cancers (TNBC) show a higher frequency of BRCAness than the other BC subtypes. Therefore, looking for BRCAness-related biomarkers could improve personalized management of TNBC patients. microRNAs (miRNAs) play a pivotal role in onco-transcriptomic profiles of tumor cells besides their suitable features as molecular biomarkers. The current study aims to evaluate the expression level of some critical miRNAs-mRNA axes in HRR pathway in tumors and plasma samples from BC patients. The expression levels of three multi-target miRNAs, including miR-182-5p, miR-146a-5p, and miR-498, as well as six downstream HRR-related protein-coding genes, have been investigated in the breast tumors and paired adjacent normal tissues by Real-time PCR. In the next step, based on the results derived from the previous step, we examined the level of cell-free miR-182-5p in the blood plasma samples from the patients. Our results highlight the difference between TNBC and non-TNBC tumor subgroups regarding the dysregulation of the key miRNA/mRNA axes involved in the HRR pathway. Also, for the first time, we show that the level of cell-free miR-182-5p in plasma samples from BC patients could be a clue for screening BC patients eligible for receiving PARP inhibitors through a personalized manner. Altogether, some sporadic BC patients, especially sporadic TNBC, have epigenetically dysregulated HRR pathway that could be identified and benefit from BRCAness-specific therapeutic agents., (© 2022. The Author(s).)

Current scientific literature lacks data on the prognostic value of the expression of RAD51 and BRCA2 in gastric adenocarcinoma. Therefore, we aimed to evaluate those and other homologous recombination-related proteins (ATM, ATR, BRCA1, CHK2, γH2AX, p53) in gastric cancer, assessing their correlation with clinical prognosis. Paraffin-embedded samples were obtained from surgical specimens collected in total or subtotal gastrectomy procedures. Between 2008 and 2017, 121 patients with advanced gastric adenocarcinoma underwent surgical resection and were included in this study. Negativity for nuclear RAD51 correlated with vascular invasion, lymph node metastasis, larger tumor size, and lower overall survival and disease-free survival in univariate analysis. However, nuclear RAD51-negative cases presented better response rates to adjuvant therapy than the positive ones. Nuclear ATR negativity correlated with larger tumor size and a higher histological grade. Positivity for ATM was associated with more prolonged disease-free survival. Positivity for nuclear BRCA2 correlated with lower overall survival and diffuse histological type, whereas its high expression was associated with vascular invasion. Nevertheless, tumors positive for nuclear BRCA2 were more frequently low grade in the intestinal histological type. Our findings indicate that RAD51 and BRCA2 are valuable immunohistochemical prognostic markers in gastric adenocarcinoma.

Objectives: To develop a validated model for evaluating the real-world effectiveness of long-term clinical management strategies for women with germline BRCA1 or BRCA2 pathogenic variants., Methods: A microsimulation model was developed that included a BRCA-specific natural history for breast and ovarian cancer, a clinical framework for carrier follow-up, and cancer risk management strategies (breast screening, risk-reducing mastectomy, and bilateral salpingo-oophorectomy). Adherence rates and outcomes for breast screening and risk-reducing surgery were obtained from BRCA carriers seen through a familial cancer service in Melbourne, Australia. The model was assessed for internal and external validity. The model was used to compare women perfectly adhering to screening recommendations versus actual adherence of the clinical cohort., Results: The model accurately predicted cancer incidence, pathology, and mortality. Using actual adherence for breast screening resulted in additional breast cancer deaths (per 1000 women: BRCA1, 2.7; BRCA2, 1.6) compared with perfect screening adherence. This decreased average life expectancy by 0.30 life-years for BRCA1 and 0.07 life-years for BRCA2. When carriers had access to risk-reducing mastectomy, the benefit from improved screening adherence was not significant., Conclusions: The developed model is a good descriptor of BRCA carriers' lifetime trajectory and its modification by use of risk management strategies alone or in combination. Evaluations of breast screening in BRCA carriers may overestimate the benefits of screening programs unless adherence is considered. By incorporating real-world clinical practice and patient behavior, this model can assist in developing clinical services and improving clinical outcomes for carriers., (Copyright © 2019 ISPOR–The Professional Society for Health Economics and Outcomes Research. Published by Elsevier Inc. All rights reserved.)

Objective: Lung cancer had been leading mounts of deaths worldwide. Advances in genes microarray had helped human further understand genes and identify novel circular RNAs. This study aimed at investigating the biological functions and molecular mechanisms of hsa_circ_0046264 in lung cancer which may be helpful in lung cancer early diagnosis and clinical treatment., Methods: Gene microarray data screened the differential gene of hsa_circ_0046264 and its downstream genes were found by bioinformatics analysis and verified by luciferase reporter assay. QRT-PCR and Western blot was used to detect the RNA and protein levels respectively. RNase R digestion confirmed the existences of circular RNA. Cell viability, invasion and apoptosis were determined by MTT assay, flow cytometry and DNA damage assay. Tumor formation in nude mice and immunohistochemistry proved the functions of hsa_circ_0046264 in vivo., Results: Hsa_circ_0046264 and BRCA2 were down-regulated in lung cancer tissues while miR-1245 was up-regulated. Hsa_circ_0046264 induced apoptosis but inhibited proliferation and invasion of lung cancer cells through targeting miR-1245 to up-regulate BRCA2. Hsa_circ_0046264 inhibited the tumor growth in vivo., Conclusion: Hsa_circ_0046264 was a tumor suppressor in lung cancer. Overexpression of hsa_circ_0046264 could up-regulate BRCA2 expression through down-regulating of miR-1245.

The RAD51 protein plays a key role in the homology-directed repair of DNA double-strand breaks and is important for maintaining genome stability. Here we report on a novel human RAD51 variant found in an aggressive and therapy-refractive breast carcinoma. Expression of the RAD51 G151D variant in human breast epithelial cells increases the levels of homology-directed repair. Expression of RAD51 G151D in cells also promotes high levels of chromosomal aberrations and sister chromatid exchanges. In vitro, the purified RAD51 G151D protein directly and significantly enhances DNA strand exchange activity in the presence of RPA. In concordance with this result, co-incubation of G151D with BRCA2 resulted in a much higher level of strand-exchange activity compared to WT RAD51. Strikingly, the RAD51 G151D variant confers resistance to multiple DNA damaging agents, including ionizing radiation, mitomycin C, and doxorubicin. Our findings demonstrate that the RAD51 G151D somatic variant has a novel hyper-recombination phenotype and suggest that this property of the protein is important for the repair of DNA damage, leading to drug resistance.

Background: Array CGH analysis of breast tumors has contributed to the identification of different genomic profiles in these tumors. Loss of DNA repair by BRCA1 functional deficiency in breast cancer has been proposed as a relevant contribution to breast cancer progression for tumors with no germline mutation. Identifying the genomic alterations taking place in BRCA1 not expressing tumors will lead us to a better understanding of the cellular functions affected in this heterogeneous disease. Moreover, specific genomic alterations may contribute to the identification of potential therapeutic targets and offer a more personalized treatment to breast cancer patients., Methods: Forty seven tumors from hereditary breast cancer cases, previously analyzed for BRCA1 expression, and screened for germline BRCA1 and 2 mutations, were analyzed by Array based Comparative Genomic Hybridization (aCGH) using Agilent 4x44K arrays. Overall survival was established for tumors in different clusters using Log-rank (Mantel-Cox) Test. Gene lists obtained from aCGH analysis were analyzed for Gene Ontology enrichment using GOrilla and DAVID tools., Results: Genomic profiling of the tumors showed specific alterations associated to BRCA1 or 2 mutation status, and BRCA1 expression in the tumors, affecting relevant cellular processes. Similar cellular functions were found affected in BRCA1 not expressing and BRCA1 or 2 mutated tumors. Hierarchical clustering classified hereditary breast tumors in four major, groups according to the type and amount of genomic alterations, showing one group with a significantly poor overall survival (p = 0.0221). Within this cluster, deletion of PLEKHO1, GDF11, DARC, DAG1 and CD63 may be associated to the worse outcome of the patients., Conclusions: These results support the fact that BRCA1 lack of expression in tumors should be used as a marker for BRCAness and to select these patients for synthetic lethality approaches such as treatment with PARP inhibitors. In addition, the identification of specific alterations in breast tumors associated with poor survival, immune response or with a BRCAness phenotype will allow the use of a more personalized treatment in these patients.

Recent work has explored a putative role for the E6 protein from some β-human papillomavirus genus (β-HPVs) in the development of non-melanoma skin cancers, specifically β-HPV 5 and 8 E6. Because these viruses are not required for tumor maintenance, they are hypothesized to act as co-factors that enhance the mutagenic capacity of UV-exposure by disrupting the repair of the resulting DNA damage. Supporting this proposal, we have previously demonstrated that UV damage signaling is hindered by β-HPV 5 and 8 E6 resulting in an increase in both thymine dimers and UV-induced double strand breaks (DSBs). Here we show that β-HPV 5 and 8 E6 further disrupt the repair of these DSBs and provide a mechanism for this attenuation. By binding and destabilizing a histone acetyltransferase, p300, β-HPV 5 and 8 E6 reduce the enrichment of the transcription factor at the promoter of two genes critical to the homology dependent repair of DSBs (BRCA1 and BRCA2). The resulting diminished BRCA1/2 transcription not only leads to lower protein levels but also curtails the ability of these proteins to form repair foci at DSBs. Using a GFP-based reporter, we confirm that this reduced foci formation leads to significantly diminished homology dependent repair of DSBs. By deleting the p300 binding domain of β-HPV 8 E6, we demonstrate that the loss of robust repair is dependent on viral-mediated degradation of p300 and confirm this observation using a combination of p300 mutants that are β-HPV 8 E6 destabilization resistant and p300 knock-out cells. In conclusion, this work establishes an expanded ability of β-HPV 5 and 8 E6 to attenuate UV damage repair, thus adding further support to the hypothesis that β-HPV infections play a role in skin cancer development by increasing the oncogenic potential of UV exposure.

Fanconi anemia (FA) is a complex genetic disease associated with a defective DNA repair pathway known as the FA pathway. In contrast to many other FA proteins, BRCA2 participates downstream in this pathway and has a critical role in homology-directed recombination (HDR). In our current studies, we have observed an extremely low reprogramming efficiency in cells with a hypomorphic mutation in Brca2 (Brca2(Δ) (27/) (Δ27)), that was associated with increased apoptosis and defective generation of nuclear RAD51 foci during the reprogramming process. Gene complementation facilitated the generation of Brca2(Δ) (27/) (Δ27) induced pluripotent stem cells (iPSCs) with a disease-free FA phenotype. Karyotype analyses and comparative genome hybridization arrays of complemented Brca2(Δ) (27/) (Δ27) iPSCs showed, however, the presence of different genetic alterations in these cells, most of which were not evident in their parental Brca2(Δ) (27/) (Δ27) mouse embryonic fibroblasts. Gene-corrected Brca2(Δ) (27/) (Δ27) iPSCs could be differentiated in vitro toward the hematopoietic lineage, although with a more limited efficacy than WT iPSCs or mouse embryonic stem cells, and did not engraft in irradiated Brca2(Δ) (27/) (Δ27) recipients. Our results are consistent with previous studies proposing that HDR is critical for cell reprogramming and demonstrate that reprogramming defects characteristic of Brca2 mutant cells can be efficiently overcome by gene complementation. Finally, based on analysis of the phenotype, genetic stability, and hematopoietic differentiation potential of gene-corrected Brca2(Δ) (27/) (Δ) (27) iPSCs, achievements and limitations in the application of current reprogramming approaches in hematopoietic stem cell therapy are also discussed., (© AlphaMed Press.)

Because of the high risk of recurrence in high-grade serous ovarian carcinoma (HGS-OvCa), the development of outcome predictors could be valuable for patient stratification. Using the catalog of The Cancer Genome Atlas (TCGA), we developed subtype and survival gene expression signatures, which, when combined, provide a prognostic model of HGS-OvCa classification, named "Classification of Ovarian Cancer" (CLOVAR). We validated CLOVAR on an independent dataset consisting of 879 HGS-OvCa expression profiles. The worst outcome group, accounting for 23% of all cases, was associated with a median survival of 23 months and a platinum resistance rate of 63%, versus a median survival of 46 months and platinum resistance rate of 23% in other cases. Associating the outcome prediction model with BRCA1/BRCA2 mutation status, residual disease after surgery, and disease stage further optimized outcome classification. Ovarian cancer is a disease in urgent need of more effective therapies. The spectrum of outcomes observed here and their association with CLOVAR signatures suggests variations in underlying tumor biology. Prospective validation of the CLOVAR model in the context of additional prognostic variables may provide a rationale for optimal combination of patient and treatment regimens.

BRCA2 (breast cancer 2, early onset) is a tumor suppressor gene that confers increased susceptibility for prostate cancer (PCa). Previous in vitro experiments demonstrated that Skp2, an E3 ubiquitin ligase aberrantly overexpressed in PCa, is involved in the proteolytic degradation of BRCA2 in PCa cells, suggesting that the BRCA2-Skp2 interaction may play a role in prostate tumorigenesis. Herein, we investigated BRCA2 and Skp2 expression during PCa development using a prostate TMA. Although luminal and basal benign prostate epithelium exhibited moderate to strong nuclear BRCA2 immunostaining, the intensity and number of positive nuclei decreased significantly in high-grade prostatic intraepithelial neoplasia and PCa. Decreased frequency and intensity of nuclear BRCA2 labeling were inversely correlated with Skp2 expression in high-grade prostatic intraepithelial neoplasia and PCa. To functionally assess the effects of BRCA2 and Skp2 expression on prostate malignant transformation, we overexpressed Skp2 in normal immortalized prostate cells. Skp2 overexpression reduced BRCA2 protein and promoted cell growth and migration. A similar phenotype was observed after reduction of BRCA2 protein levels using specific BRCA2 small-interfering RNA. Forced BRCA2 expression in Skp2-overexpressing stable transfectants inhibited the migratory and growth properties by >60%. These results show that loss of BRCA2 expression during prostate tumor development is strongly correlated with both migratory behavior and cancer growth and include Skp2 as a BRCA2 proteolytic partner in vivo., (Copyright © 2011 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

The Brca1 and Brca2 tumor suppressor genes are involved in the maintenance of genomic integrity as they facilitate error free DNA repair. This study was designed to understand the role of Brca1 and Brca2 in betel nut (BN) induced chronic and transgenerational carcinogenesis in mice. Young male and female Swiss Albino mice were chronically as well as transgenerationally exposed to aqueous extract of betel nut (AEBN) in drinking water (2 mg ml(-1)) for up to 24 weeks. In chronically exposed mice, the levels of Brca1 and Brca2 proteins were elevated to approximately 1.4-fold over the age matched controls after 2 weeks of exposure to AEBN, followed by a decline below the controls. In transgenerationally exposed mice, both Brca1 and Brca2 proteins remained below the controls from the onset of AEBN exposure and rapidly declined further, indicating a loss of tumor suppressor protection. Nucleotide sequencing of exon 11 of Brca1 and exon 27 of Brca2 did not reveal mutation in liver nodules of chronically exposed mice, while a G → C mutation Brca1 was observed in liver nodules as well as in solid tumors developing in transgenerationally exposed mice. Thus, the genomic instability arising due to the lowering in the levels of Brca1 and Brca2 proteins and mutation in exon 11 of Brca1 gene contributed to the increased risk of cancer in mice exposed transgenerationally to AEBN., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Background: Beclin 1, an important autophagy-related protein in human cells, is involved in cell death and cell survival. Beclin 1 mapped to human chromosome 17q21. It is widely expressed in normal mammary epithelial cells. Although down-regulated expression with mono-allelic deletions of beclin 1 gene was frequently observed in breast tumors, whether there was other regulatory mechanism of beclin 1 was to be investigated. We studied the expression of beclin 1 and explored the possible regulatory mechanisms on its expression in breast tumors., Methods: 20 pairs of tumors and adjacent normal tissues from patients with sporadic breast invasive ductal cancer (IDCs) were collected. The mRNA expression of beclin 1 was detected by real-time quantitative RT-PCR. Loss of heterozygosity (LOH) was determined by real-time quantitative PCR and microsatellite methods. The protein expression of beclin 1, p53, BRCA1 and BRCA2 was assessed by immunohistochemistry. CpG islands in 5' genomic region of beclin 1 gene were identified using MethylPrimer Program. Sodium bisulfite sequencing was used in examining the methylation status of each CpG island., Results: Decreased beclin 1 mRNA expression was detected in 70% of the breast tumors, and the protein levels were co-related to the mRNA levels. Expression of beclin 1 mRNA was demonstrated to be much higher in the BRCA1 positive tumors than that in the BRCA1 negative ones. Loss of heterozygosity was detected in more than 45% of the breast tumors, and a dense cluster of CpG islands was found from the 5' end to the intron 2 of the beclin 1 gene. Methylation analysis showed that the promoter and the intron 2 of beclin 1 were aberrantly methylated in the tumors with decreased expression., Conclusions: These data indicated that LOH and aberrant DNA methylation might be the possible reasons of the decreased expression of beclin 1 in the breast tumors. The findings here shed some new light on the regulatory mechanisms of beclin 1 in breast cancer.

Background: MicroRNAs (miRNA) are 20 approximately 25 nucleotide non-coding RNAs that inhibit the translation of targeted mRNA, and they have been implicated in the development of human malignancies. High grade serous ovarian carcinomas, the most common and lethal subtype of ovarian cancer, can occur sporadically or in the setting of BRCA1/2 syndromes. Little is known regarding the miRNA expression profiles of high grade serous carcinoma in relation to BRCA1/2 status, and compared to normal tubal epithelium, the putative tissue of origin for high grade serous carcinomas., Methodology/principal Findings: Global miRNA expression profiling was performed on a series of 33 high grade serous carcinomas, characterized with respect to BRCA1/2 status (mutation, epigenetic silencing with loss of expression or normal), and with clinical follow-up, together with 2 low grade serous carcinomas, 2 serous borderline tumors, and 3 normal fallopian tube samples, using miRNA microarrays (328 human miRNA). Unsupervised hierarchical clustering based on miRNA expression profiles showed no clear separation between the groups of carcinomas with different BRCA1/2 status. There were relatively few miRNAs that were differentially expressed between the genotypic subgroups. Comparison of 33 high grade serous carcinomas to 3 normal fallopian tube samples identified several dysregulated miRNAs (false discovery rate <5%), including miR-422b and miR-34c. Quantitative RT-PCR analysis performed on selected miRNAs confirmed the pattern of differential expression shown by microarray analysis. Prognostically, lower level miR-422b and miR-34c in high grade serous carcinomas were both associated with decreased disease-specific survival by Kaplan-Meier analysis (p<0.05)., Conclusions/significance: High grade serous ovarian carcinomas with and without BRCA1/2 abnormalities demonstrate very similar miRNA expression profiles. High grade serous carcinomas as a group exhibit significant miRNA dysregulation in comparison to tubal epithelium and the levels of miR-34c and miR-422b appear to be prognostically important.

Background: DNA repair genes critically regulate the cellular response to chemotherapy and epigenetic regulation of these genes may be influenced by chemotherapy exposure. Restoration of BRCA1 and BRCA2 mediates resistance to platinum chemotherapy in recurrent BRCA1 and BRCA2 mutated hereditary ovarian carcinomas. We evaluated BRCA1, BRCA2, and MLH1 protein expression in 115 sporadic primary ovarian carcinomas, of which 31 had paired recurrent neoplasms collected after chemotherapy. Additionally, we assessed whether promoter methylation of BRCA1, MLH1 or FANCF influenced response to chemotherapy or explained alterations in protein expression after chemotherapy exposure., Results: Of 115 primary sporadic ovarian carcinomas, 39 (34%) had low BRCA1 protein and 49 (42%) had low BRCA2 expression. BRCA1 and BRCA2 protein expression were highly concordant (p < 0.0001). MLH1 protein loss occurred in 28/115 (24%) primary neoplasms. BRCA1 protein loss in primary neoplasms was associated with better survival (p = 0.02 Log Rank test) and remained significant after accounting for either stage or age in a multivariate model (p = 0.04, Cox proportional hazards). In paired specimens, BRCA1 protein expression increased in 13/21 (62%) and BRCA2 protein expression increased in 15/21 (71%) of recurrent carcinomas with low or intermediate protein in the paired primary. In contrast MLH1 expression was rarely decreased in recurrent carcinomas (1/33, 3%). Similar frequencies of MLH1, BRCA1, and FANCF promoter methylation occurred in primary carcinomas without previous chemotherapy, after neoadjuvant chemotherapy, or in recurrent neoplasms., Conclusion: Low BRCA1 expression in primary sporadic ovarian carcinoma is associated with prolonged survival. Recurrent ovarian carcinomas commonly have increased BRCA1 and/or BRCA2 protein expression post chemotherapy exposure which could mediate resistance to platinum based therapies. However, alterations in expression of these proteins after chemotherapy are not commonly mediated by promoter methylation, and other regulatory mechanisms are likely to contribute to these alterations.

Expression of the BRCA2 tumor suppressor gene is tightly linked to its roles in DNA damage repair and maintenance of chromosomal stability and genomic integrity. Three transcription factors that activate (USF, NF-kappaB, and Elf1) and a single factor that represses (SLUG) BRCA2 promoter activity have been reported. In addition, a 67-bp region (-582 to -516) associated with inhibition of promoter activity has been identified. However, it remains unclear how the 67-bp region contributes to regulation of BRCA2 expression. Here, we describe the affinity purification of a 120-kDa protein that binds to a silencer-binding region within the 67-bp repression region of the BRCA2 promoter. Mass spectrometry revealed the identity of the protein as poly-(ADP-ribose) polymerase-1 (Parp-1). Gel shift, antibody super-shift, and chromatin immunoprecipitation (ChIP) assays demonstrated that Parp-1 is associated with the BRCA2 promoter both in vitro and in vivo. Furthermore, Parp-1 inhibitors (either 3-AB or NU1025) and Parp-1 gene specific siRNA resulted in increased levels of endogenous BRCA2 expression. Inhibition of Parp-1 activity (by 3-AB) reduced histone 3 lysine 9 acetylation and blocked Parp-1 binding to the BRCA2 promoter. These results indicate that Parp-1 down-regulates BRCA2 expression through an interaction with a repression region of the BRCA2 promoter.

Faithful genome transmission requires a network of pathways coordinating DNA replication to DNA repair and recombination. Here, we used molecular combing to measure the impact of homologous recombination (HR) on the velocity of DNA replication forks. We used three hamster cell lines defective in HR either by overexpression of a RAD51 dominant-negative form, or by a defect in the RAD51 paralogue XRCC2 or the breast tumor suppressor BRCA2. Irrespectively of the type or extent of HR alteration, all three cell lines exhibited a similar reduction in the rate of replication-fork progression, associated with an increase in the density of replication forks. Importantly, this phenotype was completely reversed in complemented derivatives of Xrcc2 and Brca2 mutants. These data reveal a novel role for HR, different from the reactivation of stalled replication forks, which may play an important role in genome stability and thus in tumor protection.

Homologous recombination has a dual role in eukaryotic organisms. Firstly, it is responsible for the creation of genetic variability during meiosis by directing the formation of reciprocal crossovers that result in random combinations of alleles and traits. Secondly, in mitotic cells, it maintains the integrity of the genome by promoting the faithful repair of DNA double-strand breaks (DSBs). In vertebrates, it therefore plays a key role in tumour avoidance. Mutations in the tumour suppressor protein BRCA2 are associated with predisposition to breast and ovarian cancers, and loss of BRCA2 function leads to genetic instability. BRCA2 protein interacts directly with the RAD51 recombinase and regulates recombination-mediated DSB repair, accounting for the high levels of spontaneous chromosomal aberrations seen in BRCA2-defective cells. Recent observations indicate that BRCA2 also plays a critical role in meiotic recombination, this time through direct interactions with the meiosis-specific recombinase DMC1. The interactions of BRCA2 with RAD51 and DMC1 lead us to suggest that the BRCA2 tumour suppressor is a universal regulator of recombinase actions.

BRCA2 is a tumor suppressor gene that when mutated confers an increased susceptibility to developing breast and prostate carcinoma. Besides its role in mediating DNA repair, new evidence suggests that BRCA2 may also play a role in suppressing cancer cell growth. Because altered interactions between neoplastic cells and the surrounding extracellular matrix (ECM) play a pivotal role in unchecked cancer cell proliferation and metastatic progression, we hypothesized that the ECM may have an effect in BRCA2 expression. By using normal and prostate carcinoma cell lines, we demonstrated that although normal cells transiently increase BRCA2 protein levels when adhering to the ECM protein collagen type I (COL1), carcinoma cells exhibit a significant reduction in BRCA2 protein. This aberrant effect is independent from de novo protein synthesis and results from COL1-beta(1) integrin signaling through phosphatidylinositol (PI) 3-kinase leading to BRCA2 ubiquitination and degradation in the proteasome. BRCA2 protein depletion after cancer cell adhesion to COL1 or in small RNA interference assays triggers new DNA synthesis, a trophic effect that is abrogated by recombinant BRCA2 expression. Blocking or inhibiting beta(1) integrin, PI 3-kinase, or proteasome activity all have a negative effect on COL1-mediated DNA synthesis in cancer cells. In normal cells, the transient increase in BRCA2 expression is independent from beta(1) integrin or PI 3-kinase and has no effect in cell proliferation. In summary, these results unravel a novel mechanism whereby prostate carcinoma cell proliferation is enhanced by the down-regulation of BRCA2 expression when interacting with COL1, a major component of the ECM at osseous metastatic sites.

Germ line mutations in BRCA2 gene predispose women to early-onset familial breast and ovarian cancer. BRCA2 is a protein of multiple functions. In addition to its role in DNA double-strand break repair, BRCA2 also plays a role in stabilization of stalled DNA replication forks, cytokinesis, transcription regulation, mammalian gametogenesis, centrosome duplication, and suppression of cell proliferation. However, how BRCA2 mutations predispose women specifically to breast and ovarian cancer remains undefined. Here we found that BRCA2 binds and stabilizes MAGE-D1, a member of the MAGE gene family of proteins. Expression of BRCA2 and MAGE-D1 synergistically suppresses cell proliferation independently of the p53 pathway. Using two MAGE-D1 RNA interferences and two cell lines expressing low or undetectable levels of MAGE-D1, we further showed that the expression of MAGE-D1 is required for BRCA2-mediated suppression of cell proliferation, indicating that MAGE-D1 is a downstream target of BRCA2 and that BRCA2 suppresses cell proliferation via stabilizing MAGE-D1. Importantly, MAGE-D1 protein expression was reduced in 6 of 16 breast carcinoma cell lines tested as compared with untransformed immortal mammary epithelial cell lines, suggesting that suppression of MAGE-D1 expression may be involved in the tumorigenesis of a subset of sporadic breast cancers.

BRCA2 has been implicated in the maintenance of genome stability and RAD51-mediated homologous recombination repair of chromosomal double-strand breaks (DSBs), but its role in these processes is unclear. To gain more insight into its role in homologous recombination, we expressed wild-type BRCA2 in the well-characterized BRCA2-deficient human cell line CAPAN-1 containing, as homologous recombination substrates, either direct or inverted repeats of two inactive marker genes. Whereas direct repeats monitor a mixture of RAD51-dependent and RAD51-independent homologous recombination events, inverted repeats distinguish between these events by reporting RAD51-dependent homologous recombination, gene conversion, and crossover events only. At either repeats, BRCA2 decreases the rate and frequency of spontaneous homologous recombination, but following chromosomal DSBs, BRCA2 increases the frequency of homologous recombination. At direct repeats, BRCA2 suppresses both spontaneous gene conversion and deletions, which can arise either from crossover or RAD51-independent sister chromatid replication slippage (SCRS), but following chromosomal DSBs, BRCA2 highly promotes gene conversion with little effect on deletions. At inverted repeats, spontaneous or DSB-induced crossover events were scarce and BRCA2 does not suppress their formation. From these results, we conclude that (i) BRCA2 regulates RAD51 recombination in response to the type of DNA damage and (ii) BRCA2 suppresses SCRS, suggesting a role for BRCA2 in sister chromatids cohesion and/or alignment. Loss of such control in response to estrogen-induced DNA damage after BRCA2 inactivation may be a key initial event triggering genome instability and carcinogenesis.

The human DNA mismatch repair gene hMSH2 is involved in the development of sporadic and hereditary nonpolyposis colorectal cancer. An increased risk of colorectal cancer has also been suggested in BRCA1 and BRCA2 mutation carriers. To address the relationship between the expression level of these genes and colorectal tumorigenesis, we studied BRCA1, BRCA2 and hMSH2 mRNA expression by real-time quantitative RT-PCR in 72 colorectal Lieberkühnien adenocarcinomas and matched normal mucosa. We investigated the relationship between mRNA levels and various clinicopathological parameters. The mean expression of BRCA1 3' and BRCA2 3' (mRNA pool), BRCA1 ex11 (with exon 11), BRCA2 ex12 (with exon 12) and hMSH2 mRNAs were increased in tumor samples. BRCA1 and BRCA2 mRNAs expressions were altered according to colon tumor site: BRCA1 3' and BRCA2 3' mRNAs levels were highest, respectively, in the right colon and left colon. No difference in hMSH2 mRNA levels was detected in relation to clinicopathological parameters. The mean SPF value was significantly higher in tumor than in non-tumor colonic tissue, and a high SPF value was correlated with high BRCA2 mRNA levels. BRCA2 3' mRNA levels tended to decrease as the Dukes' stage increased. In conclusion, the mechanisms of colorectal carcinogenesis seem to differ according to the right or left position of the tumor.

The expression of the breast cancer susceptibility protein BRCA2 is highly regulated in human breast, ovary, and pancreatic cells. BRCA2 is not expressed in the non-dividing cells, and expression is cell cycle stage-dependent and is elevated in the sporadic cancer cells. Mutational analysis of the upstream sequence of the human BRCA2 gene revealed an E2-box-containing silencer at the -701 to -921 position. The E2-box is essential for the cell-cycle stage-dependent activity of the silencer. We affinity-purified a 29-kDa silencer-binding protein (SBP) from the nuclear extracts of human breast cells BT-549 and MDA-MB-231. We explored whether the E2-box-binding repressor protein SLUG, which is of similar molecular size, is involved in the silencing process. Supershift assay with the purified SBP and anti-SLUG antibody revealed the identity of the SBP as SLUG. We found that silencer is inactive in the human breast cancer cells such as MDA-MB-468 and MCF-7 that do not express SLUG, further suggesting the involvement of SLUG in the BRCA2 gene silencing. Inducible expression of human SLUG in the dividing MDA-MB-468 cells reduced BRCA2 RNA levels with the activation of the silencer. Furthermore, small interfering RNA-mediated knockdown of SLUG mRNA in the BT-549 cells caused inhibition of the silencer function. Chromatin immunoprecipitation assays suggested that SLUG mediates its action by recruiting C-terminal-binding protein-1 (CtBP-1) and histone deacetylase-1 (HDAC-1) at the silencer E2-box. The general HDAC inhibitor, trichostatin A, inhibited the SLUG-mediated regulation of the silencer function. It thus appears that SLUG is a negative regulator for BRCA2 gene expression.

The influence of germ line BRCA2 unclassified variants (UCV), including missense mutations and in-frame deletions and insertions on BRCA2 function and on cancer risk, has not been defined although these mutations account for 43% of all identified BRCA2 sequence alterations. To investigate the effects of UCVs on BRCA2 function, we compared mutant and wild-type forms of BRCA2 using assays of cellular survival and viability, homologous recombination repair, and genome instability. We confirm that the effects of known deleterious mutations can be distinguished from neutral polymorphisms and wild-type BRCA2 in these assays, and we characterize the influence of a series of UCVs on BRCA2 function. We also describe how the results from the assays can be combined with data from analysis of cosegregation of the UCVs with cancer, co-occurrence of the UCVs with other deleterious mutations, and interspecies sequence variation in a comprehensive framework in an effort to better distinguish between disease predisposing and neutral UCVs. This combined approach represents a useful means of addressing the functional significance and cancer relevance of UCVs in BRCA2.

Background: The clinical course of breast cancer is difficult to predict on the basis of established clinical and pathological prognostic criteria. Given the genetic complexity of breast carcinomas, it is not surprising that correlations with individual genetic abnormalities have also been disappointing. The use of gene expression profiles could result in more accurate and objective prognostication., Results: To this end, we used real-time quantitative RT-PCR assays to quantify the mRNA expression of a large panel (n = 47) of genes previously identified as candidate prognostic molecular markers in a series of 100 ERalpha-positive breast tumor samples from patients with known long-term follow-up. We identified a three-gene expression signature (BRCA2, DNMT3B and CCNE1) as an independent prognostic marker (P = 0.007 by univariate analysis; P = 0.006 by multivariate analysis). This "poor prognosis" signature was then tested on an independent panel of ERalpha-positive breast tumors from a well-defined cohort of 104 postmenopausal breast cancer patients treated with primary surgery followed by adjuvant tamoxifen alone: although this "poor prognosis" signature was associated with shorter relapse-free survival in univariate analysis (P = 0.029), it did not persist as an independent prognostic factor in multivariate analysis (P = 0.27)., Conclusion: Our results confirm the value of gene expression signatures in predicting the outcome of breast cancer.

Purpose: BRCA1 and BRCA2 are considered to be breast cancer susceptibility genes that may also contribute to pancreatic cancer development because family studies revealed mutation carriers to have an increased risk of developing pancreatic cancer. However, as demonstrated for breast and ovarian cancer, inactivation of BRCA in sporadic diseases is based on alteration in gene expression or functional alteration., Experimental Design: To study a potential correlation of BRCA1 and BRCA2 to chronic pancreatitis and development of sporadic pancreatic adenocarcinoma, we have analyzed the expression of these genes by quantitative PCR and performed immunohistochemical analyses in normal pancreatic tissues, chronic pancreatitis, and pancreatic cancer specimens., Results: BRCA1 expression was down-regulated in chronic alcoholic pancreatitis, in particular on the RNA level. Furthermore, our data indicate suppressed BRCA1 expression in pancreatic cancer on both the RNA and protein levels. Quantitative analysis of BRCA1 protein expression demonstrated regular staining in 50% of tumor specimens tested and reduced staining in 50% of tumor specimens tested. Correlation with the clinical outcome revealed a significantly better 1-year overall survival for patients with BRCA1-regular as compared with BRCA1-reduced or BRCA1-absent tumors. In contrast, no substantial differences in BRCA2 expression were found in chronic pancreatitis and pancreatic cancer samples., Conclusions: Our data demonstrate alteration of BRCA1 expression in chronic pancreatitis and sporadic pancreatic adenocarcinoma. We, for the first time, provide evidence for a role of BRCA1 in pancreatic carcinogenesis of noninherited tumors and for clinical outcome.

BRCA1 and BRCA2 breast cancer susceptibility genes are responsible for most of the hereditary breast cancers. No or very few sporadic breast tumors have been shown to harbor mutations in the coding sequence of BRCA1 or BRCA2. In contrast to normal breast epithelial cells, BRCA1 mRNA levels in tumors appeared to be down-regulated by methylation, while BRCA2 showed significant overexpression in sporadic breast cancers. We report herein an infantile gynecomastia in a two-year-old boy, studied by immunohistochemistry of anti-BRCA1 and anti-BRCA2 antibodies. We demonstrated that BRCA1 proteins, like BRCA2, are widely expressed in the nuclei of epithelial cells surrounding the lumen of the ducts in infantile gynecomastia. The intensive nuclear staining of both proteins in the mammary tissues means that BRCA1 and BRCA2 proteins are largely expressed in infantile gynecomastia.

Introduction: A founder mutation in the BRCA2 gene (BRCA2 999del5) accounts for 7-8% of female breast cancers and for 40% of male breast cancers in Iceland. If expressed, the mutant gene would encode a protein consisting of the first 256 amino acids of the BRCA2 protein. The purpose of this study was to determine whether this mutant protein is produced in heterozygous individuals and, if so, what might be the functional consequences of mutant protein production., Methods: The presence of BRCA2 999del5 transcripts in fibroblasts from heterozygous individuals was assayed by cDNA synthesis and sequencing. The potential protein-coding portion of BRCA2 999del5 was cloned into the pIND(SP1)/V5-His vector and expressed in COS7 cells. The presence of the mutant protein in cell lysates from heterozygous fibroblasts and from COS7 cells was tested by a number of methods including immunoprecipitation, affinity purification with nickel-coated agarose beads, Western blotting and ELISA, using antibodies to the N-terminal end of BRCA2, antiserum specific for the 16 nonrelevant amino acids at the carboxyl end and antibodies to fusion partners of recombinant proteins., Results: The frequency of the BRCA2 999del5 transcript in heterozygous fibroblasts was about one-fifth of the wild-type transcript; however, no mutant protein could be detected. Overexpression of BRCA2 999del5 mRNA in COS7 cells failed to produce a mutant protein unless degradation by proteasomes was blocked., Conclusion: Our results show that the protein product of BRCA2 999del5 is extremely unstable. Therefore, an increase in breast cancer risk in BRCA2 999del5 carriers is due to haploinsufficiency at the BRCA2 locus.

Phytoestrogens are natural compounds with anticancer, proliferation, differentiation, and chemopreventive effects, for which several mechanisms have been proposed. In the present study, modulation of Brca1 and Brca2 expression by different phytoestrogen-rich diets has been investigated in ovariectomized Wistar rats. Two hundred mammary glands were harvested in three independent experiments. Brca1 and Brca2 mRNAs were quantified by real-time quantitative reverse transcription-PCR, and their proteins by immunohistochemistry. The first experiment compared the influence of different phytoestrogens [flax-seed, isoflavones (IFs), or rutin]. A 10% increase in Brca1 mRNA expression was shown after flax-seed consumption, whereas no variation was noted for Brca2 mRNA, nor for Brca1 and Brca2 proteins. In the second experiment, two soy IFs sources (Novasoy or Soylife) were given at different concentrations to the animals. Only Brca2 mRNA was increased and only at high doses. Finally, the effect of IFs was compared with that of estradiol. An increase in mRNA for both genes was noted after estradiol treatment and with the highest dose of IFs. In conclusion, our results show that IFs, given in the diet at different doses, are able to increase Brca1 and Brca2 mRNA in ovariectomized female Wistar rat. However, no variation in Brca1 or Brca2 protein expression was demonstrated, whatever the experimental conditions were.

The phytochemical resveratrol, found in grapes, berries and peanuts, has been found to possess cancer chemopreventive effects by inhibiting diverse cellular events associated with tumour initiation, promotion and progression. Resveratrol is also a phyto-oestrogen, binds to and activates oestrogen receptors that regulate the transcription of oestrogen-responsive target genes such as the breast cancer susceptibility genes BRCA1 and BRCA2. We investigated the effects of resveratrol on BRCA1 and BRCA2 expression in human breast cancer cell lines (MCF7, HBL 100 and MDA-MB 231) using quantitative real-time RT-PCR, and by perfusion chromatography of the proteins. All cell lines were treated with 30 microM resveratrol. The expressions of BRCA1 and BRCA2 mRNAs were increased although no change in the expression of the proteins were found. These data indicate that resveratrol at 30 micro M can increase expression of genes involved in the aggressiveness of human breast tumour cell lines.

To investigate at the population level the impact of BRCA1/BRCA2 gene alterations in male breast cancer, we analyzed a population-based series of 25 male breast cancer cases from Florence, Central Italy. We combined mutational screening with the study of germ-line allele transcript levels and of tumor-associated losses of heterozygosity. Screening by protein truncation test and single-strand conformational polymorphism assay, followed by sequencing, revealed 4 pathogenetic mutations (4 of 25 = 16%; 95% confidence interval, 5-37%), 1 in BRCA1 and 3 in BRCA2, including mutations recurring in Central Italy (BRCA1 3345delAG and BRCA2 6696delTC). The a priori probability of carrying a mutation, estimated using BRCAPRO software, showed a good agreement between expected and observed mutations (14% versus 16%). A 7-fold association between germ-line mutations and family history of breast-ovarian cancer emerged. To investigate associations between BRCA1/BRCA2 status and clinicopathological characteristics, we analyzed the histopathological and immunophenotypic parameters of the tumors. A significant association emerged between mutation carrier status and high histological grade (P = 0.02). Furthermore, one BRCA2 carrier was affected with Paget's disease, an extremely rare male breast cancer histotype. Overall, BRCA1/2 mutations were observed to be strongly associated with positive c-erbB-2 immunostaining (P = 0.004). To evaluate germ-line allele expression, we used primer extension assays targeting frequent BRCA1 and BRCA2 polymorphisms. A BRCA2 allele transcript imbalance was found in one of four heterozygotes tested, all of them negative for germ-line mutations. BRCA1 transcript imbalances were not detected in nine heterozygotes analyzed. Losses of heterozygosity at one or more of nine loci in the BRCA2 region were found in 8 of 22 tumors tested. Interestingly, a case that was negative for BRCA1/BRCA2 germ-line mutations and that had a priori mutation probability <10% showed loss of heterozygosity at all three of the intragenic BRCA2 markers analyzed, which could be related to a somatic involvement of BRCA2. No losses of heterozygosity were detected at BRCA1. In conclusion, constitutional BRCA1/BRCA2 mutations accounted for 16% of the male breast cancer cases in this area of Central Italy. The detection of a BRCA2 germ-line transcript imbalance and of a somatic loss of BRCA2 among the cases that resulted negative for germ-line mutations suggests a role of this gene more relevant than indicated by conventional mutational analysis. A distinct pattern of characteristics indicative of aggressive behavior, including high-grade and c-erbB-2 expression, was evident in tumors from germ-line BRCA2 mutation carriers. This suggests that phenotypic characteristics may contribute to the identification of hereditary BRCA2-related male breast cancers and that these tumors might share a unique molecular pathway of cancer progression.

Background: Germline mutations in the BRCA genes dramatically increase the risk of breast cancer. In the general population, breast cancer risk is affected by age at menarche, by age at first birth, by the number of births and by the duration of breast feeding. Whether this is true for mutation carriers is not clear., Methods: In a case-control study, nested in a population-based cohort of the Icelandic Cancer Detection Clinic, two groups of cases were defined, matched on year of birth, on age at diagnosis and on age when giving information on reproductive factors: 100 carriers of the Icelandic founder BRCA2 mutation 999del5, and 361 BRCA2-negative cases. The mean age at diagnosis was 48 years. There were 1000 women in a matched group of unaffected controls. Conditional logistic regression was used for the analysis., Results: An increased number of births was associated with a decreased risk of breast cancer in BRCA2-negative cases but not in BRCA2-positive cases. A negative association between risk and duration of breast feeding was observed only in the mutation carriers. These associations were not statistically significant, but the effects of the two variables differed significantly according to mutation status (P = 0.007 and P = 0.045 for interaction with number of births and with duration of breast feeding, respectively). This was maintained when limiting the analysis to women diagnosed older than the age of 40 years., Conclusion: The association between breast cancer and the number of pregnancies and between breast cancer and the duration of breast feeding was not the same for carriers and noncarriers of a detrimental BRCA2 mutation. In the context of other epidemiological and laboratory studies, this may indicate that the product of the BRCA2 gene has a function relating to the differentiation of epithelial tissue in the breast.